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How to Prime RV Water Pump: A Comprehensive Guide

Learn how to prime your RV water pump effectively with this comprehensive guide. Discover step-by-step instructions, expert tips, and common FAQs answered by experienced RV enthusiasts.

As an avid traveler and adventurer, there’s nothing quite like the freedom of hitting the open road in your RV.

However, to ensure a smooth and comfortable journey, it’s essential to have a well-functioning water system.

The RV water pump plays a crucial role in delivering a steady water supply for your onboard facilities.

Knowing how to properly prime the RV water pump is vital for maintaining an uninterrupted water flow.

This article is a comprehensive guide on how to prime your RV water pump effectively.

From understanding the basics to troubleshooting common issues, we’ve got you covered.

So, let’s dive in and ensure your water system is in top-notch condition for your next adventure!

How to prime RV water pump cover

Importance of RV Water Pumps

Your RV water pump plays a pivotal role in drawing water from your onboard freshwater tank and efficiently distributing it to your RV:

With a reliable RV water pump, your on-the-road living experience could be significantly impacted, ranging from difficulties in washing dishes to uncomfortable showers and ineffective toilet flushes.

Like any other mechanical component, the RV water pump requires regular maintenance to ensure its optimal function.

Over time, the pump’s parts can wear out; seals may develop leaks, or the pump motor itself may start to deteriorate.

You can catch and address these potential issues early with periodic checks and maintenance, saving you from unexpected breakdowns and costly repairs.

Regular maintenance also extends the life of your water pump, providing you with a steady water supply for many travels and adventures.

Water gushing out indicating successful priming of the RV water pump

Why Priming an RV Water Pump is Essential

Priming an RV water pump is a crucial process that involves filling the pump and the plumbing system with water to remove any trapped air.

The process is essential for a couple of reasons.

  • Pumps aren’t designed to run dry. Without fluid, the pump can overheat, leading to damage or failure. Priming ensures there’s an initial amount of water in the pump to prevent it from running dry.
  • Initiate Pumping Process: Air hinders the proper water flow in a pump. Priming helps to expel any trapped air in the pump and its suction line, allowing the pump to start moving fluid efficiently.
  • Ensure Optimal Operation: Priming improves the operational efficiency of the pump. It allows the pump to operate at its maximum flow rate and pressure for optimal performance.
Close-up of an RV water pump ready to be primed

When Do I Need to Prime an RV Water Pump?

You need to prime an RV water pump under the following circumstances:

New Installation

If you’ve just installed a new water pump in your RV, it must be primed before use. This ensures that the pump and its suction line are filled with water, allowing the motor to move fluid efficiently.

After Repairs

If the pump has undergone any repair, it should be primed again to ensure it functions correctly. This is because the repair work may have caused trapped air in the pump and suction line.

Priming helps to remove this trapped air, allowing the pump to run smoothly.

When Water Runs Out

If your RV runs out of water while using it, you may need to prime your water pump. This is because running the pump dry can cause the pump to overheat, leading to damage or failure.

After Long Periods of Inactivity

If your RV has been sitting unused for a long while, it’s a good idea to prime the pump before using it again, as the water inside may have evaporated.

After De-winterization

If you’ve winterized your RV and are getting it ready for use in warmer weather, you’ll need to prime the pump after flushing out the RV antifreeze from your water system.

Read more: How to Dewinterize your RV

RV owner happily completing the water pump priming process.

Other Signs Your RV Water Pump Needs Priming

Priming helps protect the pump from serious damage and ensures that your RV’s water system works like a charm. 

Here are a few signs that suggest your RV water pump may need priming:

  1. Inconsistent Water Flow: If the water flow from your faucets or shower fluctuates, with water pressure dropping and then picking up again, air may have entered your system. This is a common sign that your water pump needs priming.
  2. Noise from the Pump: If your water pump makes more noise than usual, particularly a loud humming or buzzing sound, this could be a sign that the pump is struggling to maintain water pressure due to trapped air.
  3. Weak Water Pressure: If you experience weak water pressure throughout your RV, it indicates trapped air. Remember, the air in the system can cause poor water pressure, resulting in weak showers and ineffective toilet flushes.
  4. Pump Runs but No Water: If you switch on the pump and it runs, but no water is pumped to your faucets, it’s a clear sign that your RV water pump needs to be primed.

If you observe any of these signs, it’s time to prime your RV water pump.

Close-up of a primed and fully functional RV faucet

Tools & Materials Needed for Priming an RV Water Pump

Before you start the priming process, having the necessary tools and materials is essential.

Here’s what you’ll need:

  1. Water!
  2. Screwdriver: This will come in handy to open the pump housing or to tighten any loose components during the priming process.
  3. Funnel: A funnel can be helpful when adding water to the pump, especially if the water intake is hard to reach.
  4. Clean Hose: This can guide the water into the pump, minimizing spillage and ensuring a clean working environment.

Locating the RV Water Pump

Before you can prime your RV water pump, you need to know where it is located.

Depending on your RV type, the pump’s location can change, but here’s a hint – it’s usually hanging out near the fresh water tank.

The RV water pump is often positioned in a compartment that can be accessed from inside or outside your vehicle.

In most cases, it will be behind a removable panel or door. Once you locate the tank, look for a device with a motor, a water inlet, outlet pipes, and an electrical connection.

That’s your RV water pump. Consult your RV’s manual if you need help locating the pump.

Close-up of a primed and fully functional RV water tanks

Step-by-Step Guide on How to Prime an RV Water Pump

Whether setting up your RV for a new adventure or after a period of non-use, following these step-by-step instructions will help you prime your 12v RV water pump like a pro.

Step 1: Fill the Freshwater Tank

Before priming the RV water pump, fill your freshwater tank with water.

It doesn’t need to be full, but it’s best to ensure plenty of water in the tank.

Take the opportunity to verify that all the valves are correctly positioned and that any gauges are working.

Step 2: Open the Cold-Water Faucet

Next, open a cold water faucet. It’s best to start with the faucet closest to the pump.

Make sure all other faucets in your RV are shut tight. This helps your pump get ready for action more effectively!

Step 3: Turn on the Water Pump

Switch on the water pump, and it will start the priming process.

The pump pulls water from the tank of fresh water, moves it around the system, and then forces it out of an open faucet.

When you turn on the water pump, you may notice air whooshing out of the tap. If so, good news! 

Your pump is doing its job just right.

Remember that it may take a moment for the water to journey through the pipes and arrive at your tap. 

Patience is key here!

Keep the water running until you see no more air bubbles coming out. 

Once it’s just water flowing, you can go ahead and shut off the tap.

Step 4: Carry on with the Rest of the Water Taps

To complete the priming process, open each faucet one at a time to release any remaining air from the RV’s water lines.

Your water system is pressurized, and your RV water pump is successfully primed.

Using a garden hose to prime RV water pump

RV Water Pump Troubleshooting Tips

Sometimes, even after following the priming process, you may still encounter issues with your RV water pump.

Don’t panic!

Here are some troubleshooting tips to help you identify and solve common problems that can arise with your RV water pump.

Pump Won’t Start or Run

  1. Check the power supply: Ensure that the pump is receiving adequate power. All electrical connections should be nice and tight, and the fuse should be in one piece, not broken or damaged.
  2. Switch issues: Sometimes, the issue could be with the switch. Make sure it’s turned on and working properly.

Water Pump Runs, But No Water Comes Out

  1. Check for blockages: Blockages in the water lines or filter can restrict water flow. Check these areas and clear any blockages you find.
  2. Check water levels: Ensure there is water in the tank. If the tank is empty, the pump will run but won’t be able to pump water.

Pump Cycles On & Off

  1. Leakage: This could indicate a leak in the system. Give all your hoses, connections, and the pump a good inspection for any leaks. 
  2. Pressure switch: If the pressure switch is faulty, it may cause the pump to cycle. You might need to adjust or replace it.

Read more: How to fix an RV water pump that keeps running

Pump is Noisy or Vibrates Excessively

  1. Mounting Issues: The pump should be securely mounted. If it’s loose, it can vibrate and make noise.
  2. Air in the System: Air trapped in the system can also cause noise and vibration. You may need to prime the pump to expel the air.

Low Water Pressure

  1. Check the Filter: A dirty filter can reduce water pressure. Clean or replace the filter as needed.
  2. Inspect the Valves: They can restrict water flow if partially closed. Make sure all valves are fully open.

Remember, if you’re unable to troubleshoot the issue yourself, it’s best to consult a professional to avoid causing further damage to your RV’s water system.

When to Consider An RV Water Pump Replacement

If, despite all your efforts, you can’t prime it, a replacement water pump may be necessary.

When considering pump replacement, there are several key factors to take into account, and some of the tell-tale signs it’s probably time:

  1. Pump’s Age: Pump can show their age. Their lifespan can swing wildly based on how much they’re used and how well they’re cared for. But if your old faithful pump is constantly causing trouble, it might be time to think: should I keep fixing it, or is it time for a shiny new one? Sometimes, a replacement could save your wallet in the long run.
  2. Frequent Breakdowns: If the pump is frequently breaking down or requiring repairs, it may be more efficient to replace the pump entirely.
  3. Decreased Efficiency: If you notice that the pump isn’t working as efficiently as it used to or it’s consuming more resources (like power or water) than before, it could be a sign that the pump needs to be replaced.
  4. Unusual Noises: Rumbling or rattling noises from a pump could indicate internal problems that require attention.
  5. Leaks: Leaks, especially at the pump shaft, often mean that seals or gaskets need to be replaced. However, persistent leaks, even after repairs, might suggest it needs to be replaced.
  6. Electrical Issues: If your unit has an electrical issue, consider looking for a new pump.

Remember, regular maintenance and timely repairs can extend the life of your pump, but when the repair costs start to outweigh the cost of a new pump, it’s usually time to consider a replacement.

Read more: 5 best RV water pump replacements

In Conclusion

Priming your RV water pump is a relatively simple process. Even troubleshooting some common problems isn’t too tricky.

Maintenance and timely repairs can help extend your water pump’s life, but eventually, you may need to consider replacing the pump entirely.

Common FAQs About Priming RV Water Pumps

How often should I prime my RV water pump?

Priming your RV water pump isn’t typically a task that needs to be done regularly. Instead, it’s usually necessary when the pump has been drained or turned on with an empty water tank, which can let air into the system. Similarly, if you’ve had to repair or replace the pump, you’ll need to prime it afterward. If your pump operates normally and consistently provides water when needed, there’s generally no need to prime it. Remember that unnecessary or excessive priming may lead to wear and tear in the pump. Always refer to your specific pump’s manual for maintenance and operation details.

What should I do if my RV water pump won’t prime?

If your RV water pump doesn’t prime despite your best efforts, a problem may be preventing the water from flowing properly. A common issue could be air leaks in the water lines or the pump itself. Check all connections and the pump for any leaks. Blockages in the water lines or filter can also prevent priming by restricting the water flow. Inspect these areas and clear any blockages. The pump should also be in good working order, so ensure no damage or wear could impair its functionality. If the problem persists, it’s recommended to seek help from a professional. It’s important to remember that trying to force a pump that won’t prime can cause damage to the pump and other components of your RV’s water system.

How long does it take to prime an RV water pump?

The time it takes to prime an RV water pump can vary based on several factors, but typically it should only take a few minutes. The time it takes can vary, depending on the size of your RV’s water system and your priming method. So remember, every RV is a little different! However, the process can take longer if you encounter difficulties such as leaks, blockages, or pump damage. Always follow your specific pump’s manual for precise instructions and timelines.

Is it normal for air to come out of the faucet during priming?

Yes, it’s entirely normal for air to come out of the faucet during the priming process of your RV water pump. When priming, you try to remove any air trapped within your RV’s water system. The air bubbles need to be expelled to create a vacuum that effectively draws the water pump into the system. So, when priming your pump, you might observe air and water sputtering out of the faucets until the air is completely purged and a steady flow of water is achieved. This is an indication that the priming process is working correctly. The pump is fully primed and ready for normal operation once the water flow becomes steady without any air bubbles.

Can I use my RV water pump without priming it?

Using your RV water pump without priming it first is not advisable. Priming your water pump is a crucial step to ensure its effective operation. This process removes any trapped air within your RV’s water system, creating a vacuum that allows the pump to draw water efficiently. Using the water pump without priming could lead to an airlock, where air trapped in the pump prevents water flow. This could impair the function of the pump and may cause damage over time. Therefore, it’s important to ensure your RV water pump is correctly primed before using it, especially after any draining, repairs, replacements, or if the pump was turned on with an empty water tank.

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